React Native“未定义不是对象（评估'this.props'）”

Question

我是原生反应的新手。我已经创建了位置访问文件。现在我想导航到“欢迎”屏幕。但是出现这样的错误“未定义不是对象（评估'this.props'）”

这是我的位置访问文件代码

import React, { useState, useEffect } from 'react';
import { Platform, Text, View, StyleSheet } from 'react-native';
import * as Location from 'expo-location';

export default function App() {
  const [location, setLocation] = useState(null);
  const [errorMsg, setErrorMsg] = useState(null);

  useEffect(() => {
    (async () => {
      let { status } = await Location.requestPermissionsAsync();
      if (status !== 'granted') {
        setErrorMsg('Permission to access location was denied');
        return;
      }

      let location = await Location.getCurrentPositionAsync({});
      setLocation(location);
    })();
  }, []);

  let text = 'Waiting..';
  if (errorMsg) {
    text = errorMsg;
  } else if (location) {
    text = JSON.stringify(location);
    this.props.navigation.navigate("Welcome")
  }

  return (
    <View style={styles.container}>
      <Text style={styles.paragraph}>{text}</Text>
    </View>
  );
}


const styles = StyleSheet.create({
container: {
  flex: 1,
  alignItems: "center",
  justifyContent: "center",
  padding: 20,
},
paragraph: {
  fontSize: 18,
  textAlign: "center",
},
});

Answer 1

问题

您在功能组件中使用this

解决方案

export default function App({navigation}) {
  ....
  if (errorMsg) {
    .....
  } else if (location) {
    ...
    navigation.navigate("Welcome") // use this way
  }

  ....
}